The present invention relates to a servo system having improved dynamic characteristics. More particularly, the invention relates to a servo system having a large secondary lag characteristic in its load system.
Known methods of improving the dynamic characteristics of a servo system have been disclosed in Japanese Laid-Open Patent Publication No. 170901/1983 and Japanese Laid-Open Patent Publication No. 27301/1986 in which a secondary advancing factor is inserted into the feedback loop.
However, in those servo systems, since a secondary lag characteristic of the load system is compensated by an inverse function compensation factor (secondary advancing factor), it is impossible to maintain good stability if there is a nonuniformity in the resonance frequency of the load system.
Furthermore, since an advancing factor is inserted into the feedback loop, the margin of stability is often insufficient.